Natural history of invertebrates test 1

Phylum actinopoda

-These are primarily planktonic floaters or in some cases sessile. All have actinopodia radiating from a spherical body. -Largest class is the Radiolaria

Osculum

A large opening on a sponge through which filtered water is expelled

Pyrenoids

Bodies associated with chromatophores which appear to function in starch formation.

Ectomesoderm

Ectomesoderm - mesenchymal (connective tissue-like network) and consists of "inwardering" ectoderm cells. Present in the Radiata and Protostomia.

Oceloblastulae

Hollow blastulae

Saprozoic

Ingests nutrients that are dissolved

Gonozoid

Reproductiove polyp of hydrozoans and other coelenterates

Actinula

Specialized hydrozoan larva released from medusa. This larval stage settles to the bottom to form a new colony.

Planula

The early, ciliated, free-swimming larva of coelenterates

Apopyle

The excurrent opening of a choanocyte chamber in leuconoid sponges

Ephyra

The stage which is produced by the scyphistoma in scyphozoans which matures into the adult medusa.

Subumbrella

Underneath region of bell of a coelentrate

Trophozoite

Vegetative, feeding and growing stage of a protozoan, often termed a "troph" for short.

Holophytic

autotrophic

Lotic

flowing water (streams and rivers)

Profundal zone

this term is not typically employed in marine systems. It is the region below the sublittoral zone in deep lakes and essentially is the bottom zone.

Blastocoel

- Blastocoel may be located centrally, or displaced toward the animal pole.

Radial cleavage

- Brachiopoda - Echinodermata In this type of cleavage there is a regular alteration of blastomeres around a polar axis so that cleavage planes are at right angles or parallel to the polar axis resulting in a centrally located blastocoel (homolecithal eggs).

Eukaroytic plant cell

- Cellular membrane present externally and internally( membrane bound organelles) - Cell wall present - Nuclear membrane present - Multiple linear arrangement of chromosomes - Large ribosomes - Cellular division via mitosis

Eukaryotic Animal Cell

- Cellular membrane present externally and internally( membrane bound organelles) - Nuclear membrane present - Multiple linear arrangement of chromosomes - Large ribosomes - Cellular division via mitosis

Dissymetrical cleavage

- Ctenophora (comb jelly)

Phylum caryoblasta

- Most primitive group of amoeboids, lacking a nucleus, mitochondria and Golgi bodies. Respiration is only possible when respiratory organelles are filled with endosymbiotic bacteria.

Bilateral cleavage

- Nematodes - This type of cleavage tends to be into right and left halves

Invertebrate

- Not a taxon - One characteristic is no backbone - Of over a million described species over 96% are invertebrates (the group is growing quickly)

Spiral cleavage

- Platyhelminthes - Nemertina - Acanthocephala - Entroprocta - Annelida This shifting of cells, spiral cleavage, may be destrophic (counterclockwise) in some groups or levotrophic (clockwise) in others.

phylum amoebozoa

- Polyphyletic grouping, contains cells with pseudopodia that lack microtubles. Microtubles are only associates with the miotic spindle. No flagella or centrioles 1. Lobosea 2. filosea

Flagellated Protozoans

- Typically have one or more flagella present in the trophozoite (most developed age) stage. Some may have pseudopodia in certain life stages. -Generally asexual by symmetrogenic binary fission - Most species are solitary, but some are colonial - asexual reproduction 1. Phytoflagellates 2. Zooflagellates

Amoeboids

- animal-like species that have a pseudopodia for locomotion. Many are benthic, but some are planktonic - Generally asymmetrical or spherical - some amoeba have flagellated stages - typically have a vesicular nucleus - Most are holozoic - reproduction through binary fission - sexual reproduction has rarely been documented 1. lobopodia 2 filopodia

Sexual (Gametic)

- conjugation, anisogamy (usually motile and different sizes), isogamy (usually motile and similar sizes). More, rarely oogamy (large female, non-motile gamete and small, motile male gamete).

Diatomes

-A single-celled alga that has a cell wall of silica. Many kinds are planktonic, and extensive fossil deposits have been found. [from modern Latin Diatoma (genus name), from Greek diatomos 'cut in two] - Can be radially, biradially, triradially symmetrical - Lack flagella except during sexual reproduction -During asexual reproduction diatoms divide within their shells by binary fission and the two original shell valves become the outer (top) valve of the new daughter cell which then produces the new lower valves. -This process leads to increasingly smaller daughter cells; however, after a certain minimal size is reached daughter cells will undergo meiosis in its shell producing haploid gametes, only one of which will survive. -This gamete develops a flagellum and frees itself from the shell to become free-swimming. -Source of diatomacous earth (= chalk) -This naked form then seeks out another diatom of the same species which is in a similar state and unites with it to form a zygote called an auxospore. -This stage will grow and eventually secrete a new outer shell.

schizogonic

-A sporozoite invades cells becoming the trophozoite. -Karyokinesis (nuclear division) which results in the release of many merozoites which re-invade other cells. -Some trophs may become the gametocytes.

Phylum apicomplexa

-All members of this group have an apical complex generally consisting of a polar, micronemes, rhoptries, subpelicular tubules, and conoid present at some stage. -Cilia and flagella absent except for flagellated microgametes in some groups. -Cysts are often present. -Used to be grouped with the Microspora, but the Microspora are now thought to be fungi. -All members are parasitic. -Many are intracellular, but some are intercellular. -In vertebrate hosts usually located in Reticulo-Endothelial system, blood, bone marrow and epithelial cells of intestine. -In the invertebrates usually located in epithelium of intestine, body cavity or urinary tract. -Single type of nucleus. -No cilia or flagella in trophozoites. -Flagella in microgametes of some representatives. -Immature have amoeboid movement in some cases. -Simple spores are formed. Most have three (3) stages in life cycle: 1. Schizogonic 2. Gametogonic 3. Sporogonic

Phylum Actinopoda Class radiolaria

-Also known as the Radiozoa. -Produce intricate mineral tests ("skeletons") with a centrally located capsule which divides the cell into an inner (endoplasm) and outer (ectoplasm) cytoplasm. -Generally they have numerous needle-like pseudopodia supported by bundles of microtubules. -The test is generally composed of silicious material. -These leave good fossil records -Species generally have axopodia (slender actinopodia supported by a central longitudinal axis of spiraling microtubules) Order: 1. Polycystinea 2. Phaeodarea

Phylum Dinoflagellata

-Approximately one-half of all described marine and freshwater species are important primary producers. They typically have two flagella, one that lies in a longitudinal groove called the sulcus and the other in a groove called the cingulum (or annulus) that runs latitudinally around the whole cell or in a spiral of several turns. -Dinoflagellates or "fire plants" are so named primarily because of the color change some species impart to marine systems when they become exposed to atmospheric oxygen during blooms. -A very well known example of dramatic color change caused by dinoflagellates is the red tide which is responsible for killing large numbers of fish when it occurs in coastal waters. Pigments are toxins. -Species often are enclosed in a thick pellicle or theca which contains cellulose. -Species found in freshwater, such as Gymnodinium spp. have a thin flexible theca or are naked, and are considered to be unarmored species, while others (mostly marine) may have a very well-developed theca composed of two thick valves and are armored. -Many species are highly ornamented or sculptured, some such as Ceratium spp. with long horn-like extensions or wing-like structures coming off the body. -Many are autotrophic but colorless species are found which are heterotrophic and a few are both. -Reproduction is usually by longitudinal division, sexual reproduction is rare. Asexual zoospores (motile asexual spores) similar to those in fungi are known to form in some species.

Phylum Retortamonada Class diplomonadida

-As the prefix "diplo" (twice) suggests these are bilaterally symmetrical flagellates with twice the usual number of internal and external features. -Species are typically oval to pear-shaped (pyriform) with an anterior sucking surface, or sucking disk. -Most structures are doubled, so that each trophozoite would have two nuclei, two axostyles and four or more flagella. -These do not have an undulating membrane and there is no cytostome. -Giardia sp. is probably the best known species and is the most common intestinal parasite of humans in North America. -There are relatively few free-living species. -Pasted to the host via a cyst

General life cycle of sponges

-Budding is not common in this group although some forms, especially freshwater species, produce bud-like gemmules asexually. -Most sponges are hermaphroditic. -Certain choanocytes become spermatogonia and give rise to sperm. -Ova are thought to develop from either choanocytes located in the chambers, or the archeocytes located in the mesoglea (or mesohyl). -Sperm leave the sponge in water currents and are carried to another sponge where they are picked up by archeocytes which transport them to the ova and fertilization takes place. -In most species the zygote is held in the body wall forming a parenchymella larva which breaks out, settles and develops into the sponge. -Some calcareous sponges produce an amphiblastula larva which is somewhat motile and develops soon after the zygote is formed.

Phylum heterolobosa

-Cells have an inducible flagellated stage with 2-4 functional flagella. Lobopodia appear to erupt during amoeboid movement. Will encyst when in unfavorable climates. Example: Nagleria Neglaria sp. is a very dangerous pathogen of humans

classes of sponges

-Generally species of sponges are divided into four classes now largley based on the composition of the body wall: 1. Calcarea (Calcispongiae) 2. Demospongia 3. Hexactinellida (Hyalospongiae) 4. Homoscleromorpha - now considered a separate class from Demospongia

Lobosea

-Have lobopodia Examples: Amoeba, Entamoeba, Arcella and Difflugia -Most species in this group are naked or atestate (exception; Arcella and Difflugia) -Very common to freshwater and marine systems -Probably the most common parasitic genus is Entamoeba which is generally an intestinal dweller. -In Arcella spp., a shelled amoeba commonly found in freshwater systems, there is a dome-shaped chitinous shell which is generally brown in color, slightly flattened from the top, and fitted with a large opening on the under surface. -Other amoeba, like Difflugia spp., have a shell composed of mineral granules which the amoeba ingests and imbeds in an outer matrix. Members of this genus have a shell that is shaped somewhat like a vase and has an opening at the lower end.

gametogonic

-Male and female gametocytes are generally picked up by the vector host during a blood meal and produce the gametes. Not all use a vector host. -Inside the vector these gametes will fuse to form the zygote.

Phylum Chlorophyta Order volvocida (chlamydomonadales)

-Many of these are colonial. Individuals are generally green, having a single cup-shaped chromoplast, a stigma and often two to four apical flagella per cell. -There are some colorless forms. -The group are mostly freshwater and are represented by Chlamydomonas and Volvox. -There are several forms of the colonial flagellates including both sexual and asexual.

Phylum Apicomplexa Class gregarinea

-Mature trophozoites are extracellular, generally large. -Parasites in digestive tract, body cavity or urinary system of invertebrates. -Schizogony absent, trophs become gamonts which unite in the process of Syzygy forming gametocysts and within these the two types of gametes form.

Class Anthozoa

-Members of this class are solitary or colonial polypoids which do not have a medusa stage. -Such organisms as the sea anemone, sea fans, corals and sea pansies are in this class. -Probably the most striking difference between this class and hydrozoan polyps is that the mouth leads in these into a tubular pharynx. -Also the gastrovascular cavity is divided into radiating compartments by septa. -The nematocysts of anthozoans do not have a lid (operculum) as seen in other cnidarians and the gonads are gastrodermal.

Hexactinellida

-Members of this class are the "glass" sponges. -As Hexactinellida indicates, the spicules of species in this class are commonly hexaxon (six pointed). Many species have a lattice-like "skeleton" formed by the fusion of these spicules. -Spicules are made of siliceous fibers, thus giving the names "glass" sponges. -A syncytium may also line the chambers of the collar cells. -They tend to be syconoid in general structure and are usually deep water sponges. -The Venus's flower basket (Euplectella) is found in this class.

Phylum Euglenozoa Class Kinetoplastida

-Members of this class characteristically have a sphere, rod or disc-shaped, self-replicating, mitochondrial-like organelle called the Kinetoplast which is associated with the origin of the flagella. Some species such as members of the genus Bodo are found in marine and freshwater environments and are free-living bacteria feeders. -Most are parasitic occurring intestinally in insects while others are extremely important blood and other tissue parasites of a variety of vertebrates including man. -Parasitic forms are usually passed from vertebrate host to vertebrate by a vector host which is typically a blood-feeding insect. -Members of the genus Leishmania are solid tissue parasites and the intracellular stages of these lack a flagellum and are called amastigotes (amastigote body form).

Phylum Ciliophora class oligohymenophora

-Members of this class have the oral apparatus well developed with compound ciliary organelles present (cirri). -In these body ciliation is uniform and the oral structures are not obvious. -These have conspicuous oral ciliary bands. Vorticella and Trichodina are common genera.

Class Scyphozoa

-Members of this group are most commonly those species referred to as jellyfish because frequently the medusa stage is the dominate form. -Medusae in this class tend to be larger than those in the hydrozoans and oral arms usually surround the mouth. -Best known genus is Aurelia

Phylum euglenozoa

-Monophyletic group with parasitism and commensalism having evolved independently several times; however, free-living forms are most frequently encountered. -All euglenozoids have relatively thick flagella; closed mitosis with an intra-nuclear spindle; paddle-shaped, discoidal mitochondrial cristae; microtubule-reinforced ventral or anterior feeding apparatus; tubular extrusomes. Class Euglenoidea Class Kinetoplastida

Demospongia

-Most of the sponges, about 90%, are found in this class. -Many are quite colorful and their distribution ranges from shallow to deep water habitats. -In some the "skeleton" may consist of siliceous spicules or spongin or both. -Spicules are monoaxons or tetraxons but not hexaxons. -All are leuconoid and there is a tendency to lack any real symmetry, however, there is a great variety of shapes seen. -Common bath sponge in this familu

Phylum heterokonta Class Opalinea

-Numbers of this group are unusual, bearing a superficial likeness to the ciliates. -Virtually all are commensals in the lower intestines of anurans (usually frogs) with a few in fish, salamanders and aquatic-base reptiles. -They are relatively large with oblique rows of cilia-like flagella which covers the entire body. -Opalinids have two to many nuclei or similar structure, have no cytostomes, contractile vacuoles and are known to reproduce sexually by anisogamous syngamy (fusion of dissimilar individuals or gametes) and therefore are no longer placed with the ciliates.

Challenges transitioning from marine to terrestrial

-Osmotic balance -Larger thermal gradients in freshwater -Need active larval stages (if larval stage is retained) -Accommodate reduced buoyancy -Mode of respiration: need more functional organs like trachea, lungs etc -Reproduction must be direct delivery

Phylum Porifera (sponges)

-Porifera are sessile aquatic animals which live primarily in marine systems. -Generally they are thought to be relatively primitive animals because they do not have true tissues or organs; however, some minimal cellular differentiation is present. -The body is composed of a series of water canals whose organization depends on the types of sponge. -The body is supported by a "skeleton" composed of organic spongin fibers or siliceous or calcareous spicules. -Generally, waste removal, exchanges of gases and intake of food is dependent on the current set up by the choanocytes to move water through the body wall via ostia the into the inner chamber (the spongocoel) and out the top through the osculum -Sponges are hermaphroditic and in most sponges a blastula larva forms from the zygote. -There are three morphological types of sponges: 1. Asconoid 2. Syconoid 3. Leuconoid

Porifera (sponges)

-Porifera are sessile aquatic animals which live primarily in marine systems. -Generally they are thought to be relatively primitive animals because they do not have true tissues or organs; however, some minimal cellular differentiation is present. -The body is composed of a series of water canals whose organization depends on the types of sponge. -hermaphroditic

Phylum retortamonada

-Retortamonads have 2-8 flagella, some of which trail behind leading flagella and the cell body, and lack Golgi bodies as well as mitochondria. -Representative genera include Chilomastix, and Giardia.

Phylum Apicomplexa class hematozoea

-Schizogonic phase in RBC's and other cells of host. It is best monitored in the blood cells. -Always uses an arthropod vector host. -Major genus is Plasmodium (P. falciparum, P. vivax, P. malariae and P. ovale) (Don't need to know species names!). Other common genera: Leucocytozoan and Haematoproteus.

Gastrulation

-The "cleavage" period ends with the formation of a blastula, which continues its development by special morphogenetic movements called gastrulation. -Gastrulation results in two germ layers, ectoderm and endoderm (diploblastic); if a gastrocoel is present it is the primordium of the digestive tract and the blastopore may be the embryonic mouth

Phylum Axostylata

-The axostylates have a bundle of microtubles, a rod-like axostyle that extends the length of the cell. In most species, it is skeletal in function, like an intracellular backbone, but in some primitive species, it undulates and imparts a snaky motion to the cell. -Axostylates lack mitochondria but have Golgi bodies.

Phylum Haptophyta

-The cells have two unequal flagella and the unique haptonema organelle, which resembles a flagellum but is not used for locomotion. -These include important species for aquaculture industries. Can cause a lot of problems in aquaculture hatcheries

Phylum Euglenozoa Class euglenoidea

-The designation comes from "eu", meaning true, and "glene", meaning eye, and was coined to reflect the presence of a red pigmented structure (or shield) lying next to a light sensitive area near the origin of the longest flagellum of these organisms as well as the presence of chloroplasts. -Euglenoids are unicellular, flagellated, asexual reproducing organisms which in most species are also photosynthetic. -These are generally flask-shaped and lack a rigid cell wall. -They have two flagella, one long flagellum arising from an anterior gullet and a second small flagella in the gullet. -The gullet (cytostome) is a mouth-like structure which is used in most members of the group to take in food particles or smaller algae. -These are primarily freshwater species and are represented by the genus: Euglena

Phylum Actinopoda class heliozoa

-The heliozoans are a group composed primarily of freshwater species some of which are planktonic and some of which are benthic. -Some textbooks refer to this group as the "sun animalicules". -Generally they tend to be spherical with fine needle-like pseudopodia called axopodia, which radiate in all directions from the body giving the appearance of a sun-like symbol. -Each axopod contains a central axial supporting rod which is covered with granular, adhesive cytoplasm. -The rod is composed of a bundle of microtubules. -The body of these organisms is composed of two parts, an outer ectoplasmic sphere called the cortex and the inner medulla which is composed of dense endoplasm where the rods are anchored. -Some species are multinucleated. -Some heliozoans are naked; however, most species have outer shells which are usually composed of foreign materials including such things as living diatoms. -Some species secrete siliceous particles which become imbedded in a matrix to form the shell. -The arrangement of the particles forming the shell is quite variable but all have openings through which the axopods are protruded. -Actinosphaerium is a common genus.

Phylum Choanoflagellata

-The prefix "choano" means collar, and in this group it points to the presence of a single flagellum surrounded by a cylindrical collar. -These are marine and freshwater species. -Some species are sessile and may have a lorica (a girdle-like "skeleton" as seen in rotifers). -These are both solitary and colonial forms and members of this order are believed to be more closely related to metazoan animals than the other protozoan groups.

sporogonic

-The zygote will divide asexually forming sporozoites which are then infective when the vector host takes a second blood meal. In those where there is no vector a sporulated oocyst may be formed. -These then initiate the Schizogonic Phase.

Phylum Ciliophora class spirotrichea

-These are ciliates with oral membranelles that wind clockwise to the cytostome, typically with cylindrical or dorsoventrally flattened bodies -In this group the oral region has conspicuous buccal membranes in the adoral zone. -Body ciliation is uniform in some species and many have compound ciliary structures (cirri). -This class is represented by four subclasses Macronucleus often has a beaded appearance -Generally these are flattened with cirri on the ventral surface and have postcilliary microtubule ribbons -Examples include: Stentor and Euplotes

Phylum Axostylata Order Hypermastigida

-These are multiflagellated protozoa with Kinetosomes arranged in a circle, plate, or longitudinal or spiral rows. Many species are of special interest because they are mutualistic in the intestines of woodroaches and termites. -The best know genus is Trichonympha.

Class Cubozoa

-These are the box jellyfish, named because of their cube-shaped medusae. -They are known for their extremely painful and potent venom (often called the sea wasps). -They have a flap-like velarium (specialized awning-like covering) on the underside to concentrate and increase the flow of water from the umbrella which results in them being faster swimmers than other jellyfish. -They have a more developed nervous system and rather than the usual simple pigmented cup (ocelli) they have 24 true eyes located on the four rhopalia (Sensory structures of both Scyphozoa and Cubozoa). -There tentacles can reach as much as 3 meters in length

calcarea

-These are the calcareous sponges, having spicules composed of calcium carbonate. -All spicules in species of this class are the same size and are monaxons or three-or-four-pronged types. -These do not have spongin fibers. -Asconoid, syconoid, and leuconoid species are found in this class. -These tend to be somewhat smaller than members of the other three classes. -They are shallow water marine dwellers, represented by the genera Leucosolenia (asconoid) and Sycon (syconoid).

Phylum Axostylata Order Trichomonadida

-These generally have an oval body with four to six flagella. -Most have four flagella but all have one of the flagella trailing and often this trailing flagellum will have an undulating membrane. -These generally have an axostyle present and a cytostome is present anteriorly. -These are directly-transmitted parasites, usually found in the alimentary canal; however, one species of the genus Trichomonas is found in the human vagina and the male urogenital tract and is a sexually transmitted disease. -No cysts have been demonstrated for these parasites. -The life cycle of "most species" are direct by passage of the trophozoites from one host to another.

Phylum foraminifera

-They have delicate granular reticulopodia (consisting of a network of filopodia). -Most species are marine and have multichambered "shells" (multilocular). -A few have single chambered "shells" (unilocular). -Most are benthic dwellers but a few, like Globigerina, are planktonic.

Class Hydrozoa

-This class includes Physalia (Portuguese man of war), Hydra spp. (Hydras) and Obelia spp. (Freshwater jellyfish). -They tend to be relatively small, sessile, and plant-like in appearance. • The primary characteristics of the class are: - The mesoglea is never cellular (no organization or differentiation of cells) - The gastrodermis lacks Cnidocytes. - Gonads are epidermal, or if gastrodermal, the eggs and sperm are shed directly to the outside and not into the gastrovascular cavity. - The polyp (hydra-like) stage is the predominate stage. Note that the Portuguese man of war is not a medusa (jellyfish), but rather a colony of several polyps varying in morphology based on their function in the colony.

Phylum Ciliphora class litostomatea

-This class is characterized by having isolated kinetics (longitudinal units of cilia, basal bodies and Kinetodesmata) in the area of oral groove bearing cilia but no compound ciliary structures like cirri. -Represented by Didinium, have the Cytostome located at or near the surface of the body at the anterior end or somewhat laterally. Somatic ciliature is usually uniform. -and by Balantidium (parasitic) where Species typically have a cytostome situated within a vestibule bearing cilia.

Phylum Ciliophora class nassophorea

-This class is characterized by transverse microtubule ribbons that run tangential to the basal bodies. -These have an oral appratus that is an elastic slit and three oral membranelles on its left side and may have an undulating membrane on the right -Example: Paramecium

Homoscleromorpha

-This class is composed of very primative, simple marine sponges. These are mostly tropical and the class has relatively few species in it. -These tend to be leuconoid and many forms are found shaded areas like grottos and tunnels usually in shallow water. -They have a very simple body type with siliceous tetractinal spicules. Most are incased in a mineral skeleton (Coral-like).

Phylum Ciliophora class phyllopharyngea

-This class is generally sessile, stalked and bear tentacles on the free end. -Cilia are lacking in adults but present in free-swimming larvae, swarm cells. -This class is represented by Ephelota, Podophrya and Acineta (Don't have to know these genera!).

Phylum Actinopoda Class acantharea

-This class superficially resembles the radiolaria, but have radiating skeletons composted of strontium sulfate. -These are marine and the primary genus is Acanthometra (Don't need to know this genus!). -These do not fossilze but may leave spine patterns behind of 10 or 20 radial spines.

Phylum heterokonta

-This diverse phylum is united with their "heterokont" motile life cycle stage (asexual zoospore), in which the flagellate cells possess two differently shaped flagella. -Many diatoms in this phylum, also a main component of plankton. -Often called the golden or brown algae because many species have an unusual Yellow to brownish pigment present; xanthophyll .

Ctenophora

-This is a small phylum of exclusively marine species. -They are thought to be an offshoot of cniderians, but have medusoid forms only and lack polyps. -These have an ectoderm, mesoglea and an endoderm. -Generally have a gastrovascular cavity -As the name "comb" jellies suggests, these have eight meridional ciliary "combs" or "comb" rows that provide for movement. -Species feed on pelagic invertebrates by using specialized adhesive structures - colloblasts. Some species have tentacles for feeding. -These are hermaphroditic and have a cydippid larva in the life cycle. -Some are pelagic in the open Ocean, others species are intertidal.

Phylum Heterokonta Class bacillariophycea

-This is a very diverse group where individuals may frequently be confined in a coating or shell that is composed of two valves, a large top valve and a smaller bottom valve that fits into the upper valve somewhat like a Petri dish. -This outer cover is composed of pectin impregnated with silicon giving it a glass-like quality. -Diatomes in general.

Phylum ciliophora

-This is apparently a very homogeneous group. -All have cilia or compound ciliary structures (cirri) for locomotion at least in some aspect of their life history. -They also have an infra-ciliature composed of ciliary basal bodies or kinetosomes which are found just under the cell surface and are associated with the cilia. -The infra-ciliature is present even in stages that do not have cilia. -Most species have a cytopyge or cell anus and a cytostome or cell mouth and all have two types of nuclei present: One macronucleus (vegetative - concerned with synthesis of RNA and DNA). One micronucleus (reproductive - concerned only with synthesis of DNA). -Reproduction is frequently by transverse fission and sexual reproduction never includes the production of free gametes. -Many are solitary and free-swimming; however, both sessile and rarely colonial forms occur. -Some have an outer covering called a lorica which is composed of either secreted material or foreign material cemented together. -Most are naked, being covered only with a living outer pellicle (has infra-ciliature). -Many ciliates have peculiar rod-like or oval organelles called trichocysts, some of which are toxic and some which are nontoxic. -The trichocysts have a variety of structures and under certain circumstances they are discharged into the water. -Stinging cells (Cnidaria). -Some discharged trichocysts are threadlike and barbed, others are bulblike at the base tapering down to a threadlike structure resembling a whip. -Cilia are similar in structure to flagella but are more numerous and shorter. -By convention the cilia are divided into somatic (occurring on the body) and oral (occurring in the mouth area). -Most species found in aquatic systems are holozoic and will have a cytostome, cytopharynx and a preoral cavity or groove. eight classes recognized: Class Karyorelictea Class Spirotrichea Class Litostomatea Class Prostomatea Class Phyllopharyngea Class Nassophorea Class Oligohymenophorea Class Colpodea

Cnidaria characterisitics

-This phylum includes such familiar organisms as hydras, jellyfish, sea anemones and corals. They display radial symmetry and are therefore placed in the division Radiata of the phyla of the animal kingdom. -All members of the phylum have a gastrovascular system, a sac-like cavity where the mouth also serves as the anus. -Tentacles are commonly seen in both medusae and hydroid (polyp) forms. -These are diploblastic, although a mesoglea layer is present. The two germ layers are the epidermis and endodermis or gastrodermis. -Two general body types are seen in the phylum, the polyp which is typically a sessile, asexually reproducing, hydra-like stage and the medusa which is a free-swimming, sexually reproducing jellyfish-like stage -These do have sensory receptors and nerve cells but not a complex network. -These are generally carnivores. -There are no specialized organs or structures for respiration, nitrogenous excreting products are released in the form of ammonia -Many species reproduce sexually and asexually by budding or strobilizaion. Some species have metagenesis (alteration of generation) where one stage sexually reproduces (medusa) and another reproduces asexually (strobila). -Statocysts for balance are usually present. 4 classes 1. Hydrozoa 2. Scyphozoa 3. Cubozoa 4. Anthozoa

testate amoeboids

-Those with outer covering or shells are primarily freshwater species. Sometimes considered a phylum. -The shells of some amoebas are secreted by the cytoplasm and are composed of chitinoid or siliceous materials; however, some species imbed foreign material in a cement-like matrix which is attached to the amoeba with protoplasmic strands. -In the latter type of covering there is usually a large opening through which the pseudopodia can be protruded.

Phylum Apicomplexa class coccidia

-Trophozoites are generally small intercellular bodies. -Schizogony present, asexual and sexual phases in life cycles. -Usually in epithelium and blood cells of invertebrates and vertebrates. -Examples: Eimeria, Haemogregarina, Sarcocystis and Toxoplasma

Kingdom Protista (Algae and Protozoa)

-Unicellular or colonial -Eukaryotic -Sexual or asexual reproduction -Locomotion may be cilia, flagella, pseudopodia or sessile -By convention this Kingdom is divided into "plant-like" organisms, the algae ("Section" Protophyta) and the "animal-like" organisms, the protozoans ("Section" Protozoa).

Prokaryotic

-external cell membrane but not membrane bound organelles - Cell wall - No nuclear membrane - Single circular or single linear chromosome - Small ribosomes - No endoplasmic reticulum - Fission for cellular division

Protozoans

-small, one-celled eukaryotic organisms. The outer covering is a plasma membrane, however some have additional nonliving outer. unicellular organism with variable symmetry and little or no differentiation of tissues into organs. - All have a nucleus 1. Vesicular 2. Compact - Most common forms of locomotion 1. pseudopodia 2. flagella 3. cilia - Many different modes of living, some free living others are parasitic - Asexual- symmetrogenic binary fission, cysts, schizogony - sexual- conjugation, anisogamy, isogamy -Outer covering is a pellicle, teste, or theca. But no true cell wall.

syconoid

1 of 3 body patterns for sponges; spongocoel is folded canals, canals lined with choanocytes, increases surface area.

Asexual bud

A bud-like structure formed by asexual reproduction of multicellular animals producing a new individual.

Statocyst

A cell containing one or more statoliths used as a sense organ of equilibrium, orientation and movement in invertebrates. The balance organs of some lower invertebrates such as the cnidarians.

Rhopalium

A compound sense organ in scyphozoans, containing an ocellus, a statocyst which is tactile and chemoreceptive.

Cytopyge

A fixed location on surface of certain protozoans from which wastes are discharged by exocytosis.

Choanocyte

A flagellated feeding cell found in sponges. Also called a collar cell, it has a collar-like ring that traps food particles around the base of its flagellum.

Contractile Vacuole

A fluid filled membrane-bound body in the cytoplasm of protozoans responsible for osmoregulation and to some extent waste removal.

Gonophore

A medusa bud that produces gametes but never seperates from the colony on which it forms

Spongin

A network of protein fibers in the skeleton of advanced sponges

Endosome

A nucleolus-like structure found within the vesicular type of nucleus of protozoans that does not disappear during mitosis.

Myoneme

A protein-lipid fiber in the cell membrane and cell involving contractibility.

Ocellus

A rudimentary "eye" containing pigmented photosensitive cells.

Prosopyle

A small intercellular space preceding the canal system of sycenoid and leuconoid sponges

Amphiblastula

A sponge larva with anterior, externally flagellated micromers and posterior macromers

Strobila

A stack-like life cycle stage of scyphozoans which is composed of strobilating ephyrae

Mesoderm

A term applied to all cells, cell layers, or cell masses which occur in the embryo between the ectoderm and endoderm. Mesoderm is the third germ layer (triploblastic). cells organized into tissues and organs; lining of the body cavity, etc

Velum

A thin circular flap which extends inward from the bell margin of hydrozoan medusae.

Manubrium

A tubular or bell-shaped mouth-bearing extension of the subumbrellar surface of a coelenterate medusa

Leuconoid

A type of canal system in sponges where choanocytes reside in chambers.

Cnidocytes

A type of cell located throughout the epidermis of cnidarians which contain stinging or snaring structures.

indeterminate cleavage

A type of embryonic development in deuterostomes, in which each cell produced by early cleavage divisions retains the capacity to develop into a complete embryo. Echinodermata, Hermichordata

determinate cleavage

A type of embryonic development in protostomes that rigidly casts the developmental fate of each embryonic cell very early. Flatworms, Molluscs and annelids

Archeocyte

A wander cell capable of differentiating into any of several cell types in sponges

holomictic

All water is mixed, complete turnover

Phylum cryptophyta

Also known as the cryptomonads, these small algae cells have plastids and are typically flattened in shape, with an anterior groove or pocket where two unequal flagella reside Distinguished from other groups by their extrusomes Example: Chilomonas

Amoebocyte

An amoeboid wandering cell found in sponges.

Coelomate

An animal that possesses a true coelom (a body cavity lined by tissue completely derived from mesoderm).

Tentacles

An elongated, flexible, fleshy, sometimes branched process born by animals, usually in groups or pairs on the "head" or surrounding the mouth. These structures serve as a tactile or prehensile organ.

Mitochondrium

An organelle which contains the enzymes of respiration (TCA Cycle, Oxidative phosphorylation). Characteristically these have cristae present which are a complex forced network to provide surface area for respiration reactions

Spherical

An organism possesses spherical symmetry if it can be cut into two identical halves by any cut that runs through the organism's center

Euryhaline

An organism that can tolerate a wide range of salinities. (osmotically independent). Could possibly move to estuaries then freshwater. Most vertebrates, but few inverts.

Infauna

Animals that live buried in the benthic sediment

Epifauna

Animals that live on the surface of the benthic substrate

Paragastic canal

Anteriorly projected branches of the infandibulum of ctenophorans

Plastids

Any of several forms of a self-replicating semi-autonomous "plant" cell organelle, a chloroplast specialized for photosynthesis, a chromoplast specialized for pigmentation or a leucoplast specialized for starch storage

Heterospecific

Associations between members of different species Predator-prey associations Competition (for habitat selection, food, etc.). Less common except where species have been introduced. Symbiosis (Commensalism, Mutualism and Parasitism)

Homospecific

Associations between members of the same species Competition (for things such as habitat selection, food, mates, etc.) Peck orders Social behavior (wasps, bees, etc.)

Phylum Axostylata v.s Phylum Retortamonada

Axostylata: Characteristics: Some have axostyle No mitochondria Have Golgi bodies 4+ flagella Typically parasitic or mutualistic Do not form cysts Found in multiple organ systems of vertebrates Retortamonada: Characteristics: Some have axostyle No mitochondria No Golgi bodies 2-8 flagella Parasitic, commensalistic, & mutualistic Cyst formation common All found in intestinal tracts of vertebrates

Chordates

Bilaterally symmetrical, notocord present

Acoelomate

Blastocoel fills up with mesoderm in form of muscle fibers, parenchyma, and other tissues. The digestive cavity remains.

Paramylon and Leucosin

Carbohydrate storage products in protozoans

Infandibulum

Central reservoir of the gastrovascular cavity of a comb jelly

Microsome

Concentrations of enzymes for protein synthesis in area ribosomes or endoplasmic reticulum.

Mesotrophic

Describes a lake with a moderate level of productivity

Amastigotes

Diagnostic stage of Leishmania

Echinodermata (starfish)

Display secondary radial symmetry but larval forms and some adults are bilateral. Body organs are well developed and a body cavity, an enterocoel, is present.

Centrolecithal

Eggs have the yolk centrally distributed as is common in insects and some crustaceans

Ectoderm

Epidermis and associated structures

Pseudocoelomate

False Coelom; blastocoel persists in adults leaving a space between the digestive tract and the body wall. The mesoderm separates from the endoderm and connects to the body wall in the form of longitudinal muscles and connective tissue.

Gastrozoid

Feeding or digestive polyp of colonial hydrozoans

Coelom

Frees digestive tract and other organs from encirclement by mesenchyme; gives space for movement, coiling, and greater activity of internal organs. Furnishes a space in which nitrogenous wastes and excess water can accumulate and from which they can be discharged by excretory ducts. Gonoducts for the discharge of sex cells connect the coelom with the exterior. Gonads project into the coelom, giving ample space for the enlargement of eggs, thus the production of large yolked eggs.

Hypolimnion

Freshwater: deeper water; cold, dense; decomposition dominates; low dissolved oxygen. Wind action has no effect.

filosea

Group that contains rapidly forming filopodia, including the testate and atestate species Euglypha, Gromia and Vampyrella

Isotonic

Having the same solute concentration as another solution.

Diploblastic

Having two primary germ layers without a true mesoderm

holoblastic cleavage

In this type of cleavage the entire embryological mass divides including the yolk. This is characteristic of homolecithal eggs and is the most common mode of cleavage in the metazoan phyla. Blastomeres are generally equal in size and evenly distributed around the forming embryonic cavity, the blastocoel.

Meroblastic cleavage

In this type of cleavage the yolk cells do not divide so that cleavage is unequal. This type of cleavage is generally seen in telolecithal and centrolecithal eggs

Endoplasm

Inner medulary region which is typically in a solid state and contains all the basic organelles

Eutrophic

Lakes which are relatively shallow, warm, rich in organic matter and nutrients, and consequently highly productive

Phylum

Major taxonomic grouping or unit of related, similar classes of animals = monophyletic

Radiata

Members of the radially symmetrical animal phyla. Cnidarians, sponges, ancestral metazoans, and choanoflagellates. - typically few or no organs - cellular differentiation minimal Many species in this group have become irregular (sponges) or have developed biradial symmetry (sea anemones or comb jellies) but are still placed in the Radiata.

Food vacuole

Membrane-bounded organelle involved in the digestion of food particles.

Trypomastigote

Most forms have a single anterior flagellum that in some species may be attached to the body by an undulating membrane

Cytostome

Mouth-like structure which is responsible for taking materials into the cytoplasm of some protozoans

Nematocycsts

One of the minute stinging cells of coelenterates, usually composed of a hollow thread-like structure coiled inside a capsule and an external hair trigger.

Echinodermata and Ctenophora

Only two animal phyla without parasitic species

mixotrophic

Organism that can use autotrophic and heterotrophic means of gaining nutrients

Pelagic

Organisms that are either suspended in the water column or are swimmers

Incurrent canal

Passageway through the external cortex which precedes the prosopyles of advanced sponges

Subkingdom Protozoa "other"

Phylum Apicomplexa

Subkingdom Protozoa "Amoeboids"

Phylum Caryoblasta Phylum Heterlobosa Phylum Amoebozoa Phylum Foraminifera Phylum Actinopoda

Subkingdom Protozoa "Ciliates"

Phylum Ciliophora

Subkingdom Protozoa "Flagellates"

Phylum Euglenozoa Phylum Haptophyta Phylum Cryptophyta Phylum Chlorophyta Phylum Heterokonta Phylum Dinoflagellata Phylum Axostylata Phylum Retortamonada Phylum Chromerida Phylum Choanoflagellata

Cnidaria

Primary radial symmetry as a rule, little differentiation of tissues into internal organs. One opening to the digestive tract or gastrovascular cavity.

Nucleus

Prominent membrane-bound sac containing the chromosomes and providing physical separation between transcription and translation. The term karyosome is sometimes used instead

Golgi bodies

Sac-like areas of lipid phosphorous and enzymes concentrations. It is responsible for secretion and packaging of certain materials for distribution into the cytoplasm of the cell.

Atrium

Same as spongocoel

asconoid

Simplest form of sponges, with canals leading directly from the outside to the interior

Blastomeres

Smaller cells produced by cleavage during mitotic cell division. Often, this early cleavage process results in two unequal sized types of blastomeres, the large ones being the macromeres and the smaller ones being the micromeres. The end product of this embryonic process in most organisms is the egg

Stereoblastulae

Solid without blastocoel. Arise from homolecithal and telocithal eggs.

Colloblast

Specialized capturing or adhesive cells of ctenophorans

Basal disc

The basal region of attachment of polyp body forms to a substrate.

Protoplasm

The bulk of the protozoan which includes cytoplasm where catabolism occurs and the nucleus where anabolism occurs. Content of the cell including the cell membrane.

Gastrovascular cavity

The cavity of coelenterates, ctenophorans and flatworms which opens to the outside only by way of a mouth and serves as a digestive system, circulatory system and coelom.

Cytoplasm

The cellodial region which is found between the nuclear membrane and the plasma membrane. This region is composed primarily of protein and can, in general, be divided into two regions.

Parenchymella

The larva form of a leuconoid sponge

Mesoglea

The loose, gelatinous middle layer of the body of sponges and coelenterates situated between the ectoderm and endoderm

Entercoel

The mesoderm arises as outpockets from the primitive gut (archenteron). These pockets become cut off in the blastocoel; their cavity is the coelom, their walls the mesoderm (Deuterostomia).

medusa

The motile, free-swimming jellyfish body type of coelenterates.

Nematoda

The nematodes, along with several other groups (i.e. Gastrotrichs and Rotifers), are bilaterally symmetrical and do have specialized organs present. The "body cavity" in these derived from the blastocoel of the developing embryo and is termed Pseudocoel. These have a nonliving outer cuticle but lack jointed appendages or true segmentation.

Hypostome

The oral cone of some coelenterate gastrozoids and arthropods. Sometimes equated with the manubrium.

Homolecithal/isolecithal

The ovum contains evenly distributed yolk as typical of the molluscs

Scyphistoma

The polyp stage in a scyphozoan life cycle which strobilate ephyrae

Oceanic Zone

The region of ocean that is beyond the continental shelf

Aboral

The surface of certain invertebrates, such as jellyfish, which is situated away from the mouth.

Gastrodermis

The tissue layer which lines the coelenteron in radiate animals

Polyp

The typical sessile form of a coelenterate.

Photic (euphotic) zone

The upper region of the ocean where light can effectively penetrate and photosynthesis exceeds respiration. Usually between 100 and 200 meters depending on turbidity.

Mollusca

These are bilaterally symmetrical or have a modified bilateral symmetry. Most have hard outer shells or valves. Segmentation is exhibited in a few groups, e.g. the chitons, but most lack this feature. A body cavity, a schizocoel, is present and organs are reasonably well differentiated.

Annelids

These are bilaterally symmetrical. Many have soft bodies but some have an outer cuticle. True segmentation, or metamerism, is common in the phylum but jointed appendages are not known. These have a schizocoel and organs are well developed.

Arthropods

These display bilateral symmetry and an exoskeleton is present. Members of the phylum are metameric and jointed appendages are common. A schizocoel is generally present in adults but always seen in early larval forms.

Bilateral

This form of symmetry has a definite anterior and posterior region. If a plane is passed along the anterior-posterior axis, it will divide the organisms into two equal parts such that the right and left halves are mirror images of each other.

Superficial cleavage

This is an equal cleavage where the yolk materials are surrounded. It is seen in some centrolecithal eggs

Radial

This type of symmetry from a top or bottom view would appear much like spherical symmetry except that rather than being spherical, these organisms would be like a stack of coins. In fact the terms cylindrical and subspherical are often applied to this type of symmetry. Can be sessile or active swimmers Suggested that the development of this type of symmetry implies a uniform environment with equal distribution of biotic stressors

biradial

This type of symmetry is usually formed by the development of evenly distributed projections in association with radial symmetry giving such organisms a more bilateral appearance. Characteristic of cephalization Body activities tend to become more coordinated and responses to external conditions become quicker and more precise

Entomesoderm

True mesoderm; all mesoderm which arises from the endoderm. Ento- and endo- mesoderm may arise via various methods. Occurs primarily in Deuterostomia. Where there are three germinal layers, it is termed triploblastic vs diploblastic where there are only two germinal layers present.

Visceral Leishmaniasis

Typically found in the reticuloendothelial (RE) system of the spleen, liver, mesenteric lymph nodes, intestine, and bone marrow. The disease is known as kalaazar or Dum-Dum fever.

dystrophic

With time, some lakes may become bogs where the levels of calcium carbonate are low, humus content is high, nutrients levels are very low and the pH is low. Becomes a field = new area for colonization by terrestrial species.

Trypanosoma

a blood parasite and members of the genus are responsible for African Sleeping Sickness and Chagas disease (in New World). The trypanosomes have an undulating membrane in the blood form and is termed a trypomastigote body form.

Schizocoel

a coelom formed by the splitting of embryonic mesoderm

Volvox

a green, single-celled aquatic organism that forms minute, free-swimming spherical colonies.

monomictic

a lake that mixes once a year

Kinetoplast

a mass of mitochondrial DNA lying close to the nucleus in some flagellate protozoa.

Spicule

a needle of silica or calcium carbonate in the skeleton of some sponges. Used as support

Toxoplasmosis

a parasite that is most commonly transmitted from pets to humans by contact with contaminated animal feces

Arcella

a shelled amoeba commonly found in freshwater systems, there is a dome-shaped chitinous shell which is generally brown in color, slightly flattened from the top, and fitted with a large opening on the under surface. Within the Lobosea

Mesolimnion (thermocline, or metalimnion)

a transition zone in the middle; fall and spring turn over that mixes water and oxygen

coelenterates

an aquatic invertebrate animal of a phylum that includes jellyfishes, corals, and sea anemones..

Bilateria

animals with bilateral symmetry. flatworms, nemerteans, echinoderms, chordates, hemichordates, brachiopods, bryozoans, arthropods, annelids, molluscs, nematodes, gastrotrichs, and rotifers - generally have internal organs and unlike the Radiata, these generally will have some form of fluid-filled cavity lying between the body wall and the internal organs, the body cavity or coelom.

Porifera

asymmetrical or with radial symmetry, very little differentiation of tissues into organs. No body cavity formed.

Deuterostomes

blastopore becomes anus

Stenohaline

cannot tolerate substantial changes in external salt concentrations

Oligotrophic

characterized by the low frequency of nutrient recycling and the relatively low levels of phosphorus, nitrogen and calcium. Typically young, deep, cold, and nonproductive lakes.

Medulla

composed of dense endoplasm where rods are anchored

cephalization

concentration of sense organs and nerve cells at the front of an animal's body

Difflugia

have a shell composed of mineral granules which the amoeba ingests and imbeds in an outer matrix. Members of this genus have a shell that is shaped somewhat like a vase and has an opening at the lower end. Within the Lobosea

tropholytic zone

in lakes and essentially encompasses a depth equivalent to the sublittoral zone and the profundal zone. It is similar to the aphotic zone of oceans in that it is defined as the deeper zone where light cannot effectively penetrate and respiration exceeds photosynthesis.

dimictic

lakes that mix twice a year

amictic

lakes that never mix

Spongocoel

large central cavity of the sponge

Dipleura larvae

larval form with an entercoel

Trophogonic zone

like the photic zone of oceans is based on the depth light can effectively penetrate into the water column.

Endoderm

lining of digestive tract

axopodia

long, thin pseudopodia supported by axial rods of microtubules

polymictic

mixes several times a year

Zooflagellates

more animal-like in that they lack chlorophyll or other pigments. These have one to many flagella and are either holozoic or saprozoic.

filopodia

more slender, pointed, sometimes branched pseudopodia formed from ectoplasm only

undulating

moving with a wavelike motion

astestate

naked

reticulopodium

network of filopodia

Holozoic

obtaining nutrition by eating other plants or animals. whole and animal like

Oral arm

one of four frilly arm-like structures extending out from the mouth of a scyphozoan medusa.

Ostium

one of the small openings in a sponge's body through which water enters

Blastophore

opening in blastula

cortex

outer ectoplasmic sphere

Visceral

pertaining to the internal organs

Porocyte

pores in sponges through which water flows. A tubular epidermal cell that surrounds an ostium in sponges

Benthic

refers to the bottom region or substrate which supports "benthic" communities. The intertidal would have a benthic, as would the sublittoral and continental slope.

Protostomata

retain blastopore as mouth

Trochopore larva

shared larval form of trochozoans (mollusks and annelids) with schizocoel

testate

shelled

Leshmania

solid tissue parasites and the intracellular stages of these lack a flagellum and are called amastigotes (amastigote body form).

Meiofauna (Interstitial Fauna)

species of invertebrates live in the spaces between sand grains

Lentic

standing water (lakes, ponds)

Asexual (agametic)

symmetrogenic binary fission, cysts, schizogony (multiple fission).

Axostyle

the axial rod functioning as a support in flagellates

Blepharoplast

the basal body origin of the flagella that supports the undulating membrane in kinetoplastid flagellates. Two central microtubles which are encircled by mini double microtubules

Ectoplasm

the corticle layer of protein and lipoprotein fibers which is generally in a gel state which forms the outer periphery of the protozoan.

Intertidal (littoral) zone

the edge of the sea which rises and falls with the tides

Abyssal zone

the lowest portion of the continental slope which generally forms the ocean bottom

Supratidal (Supralittoral) zone

the region above the intertidal zone

Subtidal (sublittoral) zone

the region below the intertidal zone which extends outward to the end of the continental shelf

Nertic Zone

the region of the ocean that covers the continental shelf

Bathyal zone

the region of the subtidal that slopes off toward the bottom or abyssal zone

bathypelagic zone

the region of the water column between 1,000 meters and 4,000 meters in depth.

mesopelagic zone

the region of the water column between 200 meters and 1,000 meters in depth.

epipelagic zone

the region of the water column between the surface and 200 meters in depth. Because of the depth, the region is generally found outside the sublittoral zone.

abyssopelagic zone

the region of the water column deeper than 4, 000 meters.

aphotic zone

the region of the water column in deeper water which is beyond the depth light can effectively penetrate. This layer lies below the Photic Zone and is characterized by darkness. There may be a region of transition between this region and the Photic Zone.

Hadal zone

the trench-like regions found in the ocean floor

Telolecithal

the yolk eccentrically located as is seen in cephalopods and some arthropods

Lobopodia

thicker, blunt pseudopodia formed from endoplasm and ectoplasm

littoral zone

this is equivalent to the Intertidal Zone of oceans. It is generally the peripheral shallow zone which extends from the shoreline of a lake to the depth where plants (rooted aquatics) no longer are found.

sublittoral zone

this zone is essentially equivalent to the Subtidal Zone of oceans. In lakes it is the zone which extends lakeward from the littoral zone into deeper water.

Limnetic zone

this zone is roughly the same as the epipelagic zone of oceans and is sometimes referred to as the pelagic zone. It is the zone lakeward from the littoral zone extending from the surface of the water to the approximate depth of the littoral zone.

Phytoflagellates

typically have one or two flagella and are usually photosynthetic, (holophytic; autotrophic). This plant-like group includes many common flagellates such as Euglena, Chlamydomonas, Volvox and Peranema. Note that some genera contain species without chlorophyll.

epilimnion

well mixed, well illuminated and nearly isothermal

Reticulopodia

which type of pseudopod exists as a network of interconnected projections

Platyhelminthes

with bilateral symmetry but there is some differentiation of tissues into organs. No body cavity is present but a filling tissue, parenchyma, supports internal structures. This type of internal structure is termed acoelomic.